Moissanite Size Chart: MM to Carat and Carat to MM (All Cuts)

Moissanite Size Chart: MM to Carat & Carat to MM (All Cuts Guide 2026)

Compare moissanite sizes in mm to diamond carat equivalents. Use our complete moissanite size chart for round, oval, pear, cushion, heart, and more.

Moissanite Size Chart: MM to Carat and Carat to MM (All Cuts)

Moissanite Size Chart: MM to Carat & Carat to MM Guide

 

A moissanite size chart helps compare stone measurements in millimeters (mm) to approximate diamond carat equivalents.

Because moissanite and diamonds have different densities, moissanite is usually measured in millimeters rather than carat weight for greater accuracy.

For example:

  • 6.5mm ≈ 1 carat equivalent
  • 8mm ≈ 2 carat equivalent
  • 9mm ≈ 3 carat equivalent

However, the visual size of a stone also depends on its shape.

For example:

  • oval moissanite often looks larger than round at the same carat size
  • pear cuts may appear longer on the finger
  • cushion cuts often look softer and slightly smaller

This guide explains moissanite mm to carat conversions across all popular cuts, including:

  • round cut
  • oval cut
  • pear cut
  • marquise cut
  • cushion cut
  • emerald cut
  • princess cut
  • radiant cut
  • heart cut

Whether you are shopping for an engagement ring, earrings, pendant, or tennis jewelry, understanding moissanite sizing helps you choose the right look.

Moissanite Size Chart

💠 Complete Moissanite Size Chart (MM to Carat – All Cuts up to 3 Carats)

📊 Approximate conversions. Slight variations may occur depending on cut proportions and depth.

Shape / Cut MM Dimensions Approx. Moissanite Carat Diamond Look Equivalent (Carat)
Round Cut 4.0 mm 0.25 ct 0.23 ct
5.0 mm 0.50 ct 0.47 ct
6.5 mm 1.00 ct 1.00 ct
7.5 mm 1.50 ct 1.40 ct
8.0 mm 2.00 ct 1.90 ct
9.0 mm 3.00 ct 2.70 ct
Oval Cut 7 × 5 mm 1.00 ct 0.90 ct
8 × 6 mm 1.50 ct 1.40 ct
9 × 7 mm 2.00 ct 1.90 ct
10 × 8 mm 3.00 ct 2.70 ct
Pear Cut 7 × 5 mm 1.00 ct 0.90 ct
9 × 6 mm 1.50 ct 1.40 ct
10 × 7 mm 2.00 ct 1.90 ct
11 × 8 mm 3.00 ct 2.70 ct
Marquise Cut 8 × 4 mm 0.70 ct 0.65 ct
10 × 5 mm 1.20 ct 1.10 ct
12 × 6 mm 1.80 ct 1.70 ct
14 × 7 mm 3.00 ct 2.70 ct
Cushion Cut 5.5 × 5.5 mm 0.75 ct 0.70 ct
6.5 × 6.5 mm 1.00 ct 1.00 ct
7.5 × 7.5 mm 1.50 ct 1.40 ct
8 × 8 mm 2.00 ct 1.90 ct
9 × 9 mm 3.00 ct 2.70 ct
Radiant Cut 6 × 4 mm 0.70 ct 0.65 ct
7 × 5 mm 1.20 ct 1.10 ct
8 × 6 mm 1.75 ct 1.60 ct
9 × 7 mm 2.50 ct 2.40 ct
10 × 8 mm 3.00 ct 2.70 ct
Emerald Cut 6 × 4 mm 0.70 ct 0.65 ct
8 × 6 mm 1.50 ct 1.40 ct
9 × 7 mm 2.25 ct 2.10 ct
10 × 8 mm 3.00 ct 2.70 ct
Princess Cut 5 × 5 mm 0.75 ct 0.70 ct
6 × 6 mm 1.00 ct 1.00 ct
7 × 7 mm 1.75 ct 1.60 ct
8 × 8 mm 2.50 ct 2.40 ct
9 × 9 mm 3.00 ct 2.70 ct
Heart Cut 6.5 × 6.5 mm 1.00 ct 1.00 ct
7 × 7 mm 1.25 ct 1.20 ct
8 × 8 mm 2.00 ct 1.90 ct
9 × 9 mm 3.00 ct 2.70 ct


🔁 Moissanite Carat to MM Conversion (Quick Reverse Chart)

Carat Weight Round (mm) Oval (mm) Cushion (mm) Emerald (mm)
0.50 ct 5.0 mm 6 × 4 mm 5 × 5 mm 6 × 4 mm
1.00 ct 6.5 mm 7 × 5 mm 6.5 × 6.5 mm 8 × 6 mm
1.50 ct 7.5 mm 8 × 6 mm 7.5 × 7.5 mm 8 × 6 mm
2.00 ct 8.0 mm 9 × 7 mm 8 × 8 mm 9 × 7 mm
3.00 ct 9.0 mm 10 × 8 mm 9 × 9 mm 10 × 8 mm


Does Moissanite Look Bigger Than a Diamond?

Sometimes - yes.

Because certain moissanite cuts have larger face-up dimensions, they may appear visually larger than diamonds of the same carat weight.

For example:

Oval Cut

Often appears larger and more elongated.

Pear Cut

May create a slimmer, longer appearance.

Round Cut

Classic proportions with balanced brilliance.

Cushion Cut

Can appear slightly softer or smaller due to shape.

Visual appearance depends on both millimeter size and stone shape.

Oval, marquise, and pear cuts appear largest face-up per carat, making them ideal for maximum sparkle impact.

What Moissanite Size Looks Best?

The best moissanite size depends on personal style.

Subtle & Everyday Look

0.5–1.5 carat equivalent

Best for:

  • minimalist jewelry
  • everyday wear
  • understated elegance

Balanced Luxury Look

1.5–3 carat equivalent

Best for:

  • engagement rings
  • statement sparkle without looking oversized

Bold Luxury Look

3+ carat equivalent

Best for:

  • maximum brilliance
  • statement jewelry
  • dramatic appearance

FAQ 

What mm size equals 1 carat moissanite?

A 6.5mm round moissanite is commonly considered close to a 1 carat diamond equivalent.

What mm size equals 2 carats?

Around 8mm is often considered close to a 2 carat equivalent.

Does oval moissanite look bigger?

Yes, oval cuts often appear visually larger than round stones at the same carat size.

What moissanite size looks most realistic?

Many buyers choose 1–2 carat equivalent sizes for a balanced and natural look.

Is 3 carat moissanite too big?

It depends on personal preference. Some prefer subtle sparkle, while others prefer a bold luxury look.

Why is moissanite measured in mm?

Because millimeter measurements are often more accurate than carat weight for moissanite sizing.

Which moissanite cut looks biggest?

Oval and pear cuts often appear larger because of their elongated shape.

Explore More Moissanite Size Guides

Back to blog
    View all